1. Field of the Invention
The present invention is broadly concerned with an improved die platen assembly adapted for use on die stamping presses in order to facilitate the makeready of such devices. Automatic self-adjustment of one of the platen assemblies is provided during use to accommodate the configuration of the opposing platen assembly. More particularly, the invention pertains to such a self-adjusting die platen assembly which includes a shoe presenting a fluid reservoir with a platen-supporting piston shiftably positioned within the reservoir; the piston and die platen are rockably shiftable for adjusting the orientation of the platen operating face to accommodate the configuration of the cooperating die plate assembly during use of the die set.
2. Description of the Prior Art
Die stamping machines have wide application for performing various operations on a number of different substrates including paper, plastic and metal film. The stamping machines have mutually cooperable die sets, or a die set in association with an anvil platen. In all instances though, it is necessary that the interengageable surfaces of the die sets or die and anvil platen be in parallel relationship. Die makeready therefore necessarily involves a series of preparatory set-up operations directed toward obtaining parallelism to the extent possible between mutual engageable surfaces of the die sets or anvil.
For example, where stamping presses are used in the paper converting industry to create blanks, or form perforations for crease lines in a workpiece it is desirable that the blanking, perforating or creasing surface of the die be parallel to the underlying die or platen face. Otherwise, significant makeready must be carried out to compensate for lack of parallelism between the mutually cooperating surfaces. Generally speaking, the differences between parallel and non-parallel are very small increments of a few thousandths of an inch. However, these seemingly small differences cause very large variations in the output product.
In the case of stamping dies having a steel rule die operable against an opposed flat platen face, it is not uncommon for portions of the operating edge of the steel rule to be of greater height than other segments of the rule. As a result, when the steel rule die is moved toward a workpiece positioned on the supporting anvil platen, those portions of the steel rule die which are highest engage the workpiece before other portions of the working edge of the rule contact the substrate. As a result, the cut, crease or perf line is not uniform throughout the extent of the steel rule.
Accordingly, the metallic rules used with such devices must either be very precisely and carefully fabricated to assure that all cuts, crease lines or perforations are properly placed on the workpiece, and are also correct as to depth of cut. Otherwise, substantial compensatory makeready must be accomplished using workpiece backup components.
In general, die makeready involves preliminary placement of the rule, followed by numerous trial runs and adjustments of the rule until proper rule placement is achieved. This process is not only time-consuming, but requires considerable operator skill.
In like manner, male and female die sets frequently require makeready adjustment as a result of disparities in the height of the operating edge or surface of one die along the length of the edge or surface which interacts with the complemental operating portion of the opposed die.
There is therefore a decided need in the art for an improved die set which provides a self-adjusting feature which provides compensation for height differences in the working surfaces of a die to facilitate and shorten the time involved in makeready operations.